Tu06: Spectrum Agile Radios: Challenges, Solutions, and Cross-Layer Design
Duration: Half Day (Monday pm, Nov. 29)

Instructor:
Mihaela van der Schaar, University of California Davis, USA
Sai Shankar N, Philips Research USA

Abstract:
As radio spectrum becomes increasingly scarce, new proposals are now surfacing to utilize opportunistic radios that exploit allocated but unused frequency spectrum. Such radios can form a secondary network by sensing spectral opportunity when a primary licensee of that spectrum is not active. While conceptually simple, the realization of opportunistic spectral access is highly challenging. This tutorial will discuss the challenges and potential solutions for several of the key problems in opportunistic spectral use as well as the benefits of such radios in supporting QoS for applications such as video. Some of the technical issues associated with the radio include: sensing over a wide frequency band; identifying the presence of primaries and characterizing available opportunities; coordinating among devices the use of identified opportunities; exploiting the identified transmission opportunities and selecting the adaptation and error protection strategies that optimize the performance of the applications. Spectrum agile radios cause a fundamental shift from legacy systems since channel management now rests with each radio, and hence the current channel conditions, interference and contention levels must be monitored regularly such that new or better transmission opportunities are identified. After covering the main principles of spectrum agile radios, the tutorial will present an integrated approach for optimized transmission of delay-sensitive data over these radios. We will discuss how such radios can acquire and utilize the available channel characteristics for improving the QoS (increased throughput, lower delays etc.) of delay-sensitive multimedia applications. Techniques to jointly optimize error-resilient source coding, packet scheduling, adaptive MAC and physical layer techniques will also be presented.

Instructor Bios:
Mihaela van der Schaar received her PhD degree in Electrical Engineering from Eindhoven University of Technology, the Netherlands. She is currently an Assistant Professor in the Electrical and Computer Engineering Department at University of California, Davis. Between 1996 and June 2003, she was a senior member research staff at Philips Research in the Netherlands and USA. At Philips, she led the research activity on adaptive video coding and streaming over Internet and wireless networks, and was also involved in the research of low-cost very high quality video compression techniques and their implementation for TV, computer and camera systems. Since 1999, she is an active participant to the MPEG-4 standard, contributing to the scalable video coding activities, and she was also a co-editor of the MPEG-4 "Fine Granularity Scalability" standard. She is currently the chair of the MPEG-21 ad-hoc group on Scalable Video Coding and of the adhoc group on Multimedia Streaming Testbed. She gave several courses in the area of scalable video coding, multimedia networking and architectures at different IEEE conferences and also for Philips Center of Technical Training. In 2003, she was also an Adjunct Professor at Columbia University. She chaired and organized numerous sessions in the video streaming area and is a guest editor of the EURASIP Special issue on multimedia over IP and wireless networks, December 2003. Her research interests include image and video coding, multimedia communications and networking, and the transmission of multimedia data over wireless and packet networks. Her research interests are in multimedia networking, compression and architectures. She authored and co-authored more than 80 book chapters and papers and holds 11 patents. She was elected as a Member of the Technical Committee on Multimedia Signal Processing of the IEEE Signal Processing Society and is an associate editor of IEEE Transactions on Multimedia and SPIE Electronic Imaging Journal. She is also a senior member of the IEEE and the General Chair of the Picture Coding Symposium 2004.

Sai Shankar N received his PhD degree from the department of Electrical Communication Engineering from Indian Institute of Science, Bangalore, India in the area of ATM networks. In 1998, He was awarded the German Fellowship, DAAD, in the department of mathematics, University of Kaiserslautern, Germany to work on queuing approaches in manufacturing. In 1999, he joined Philips Research, Eindhoven, the Netherlands, where he served as Research Scientist in the department of New Media Systems and Applications. He worked on various problems involving Hybrid, Fiber, Co-axial Cable (IEEE 802.14) Networks and IP protocols. In the year 2001 he joined Philips Research USA, Briarcliff Manor, NY and is working in the area of Wireless LANs. He is an active contributor of the wireless LAN standard and has submitted more than 15 proposals in shaping QoS related issues in the IEEE 802.11e. He is also an active participant in the Ultra Wide Band (UWB) working group of IEEE 802.15.3 and is contributing in shaping the new MAC in the Multi Band OFDM Forum. He is one of the authors of the new UWB MAC. Also Sai Shankar is a participant in IEEE 802.11n (High Throughput Study Group), a new standard that will define the wireless MAC that provides high throughput using MIMO PHY. He was the session chair in IEEE ICICS 2001, Chair and TPC member of 2 nd and 3 rd New York Metro Area Workshop, TPC member of Mobile Networks and Applications workshop of IEEE Globecom 2004, TPC Member of ACM WMASH held in conjunction with Mobicom and Co-Chair of Broadwise. He has authored more than 28 conference and journal papers and holds more than 25 patents.